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Parvovirus is a very small non-enveloped DNA virus with extreme environmental stability. It can persist in the environment for up to a year and is also very temperature-resistant. Animals become infected oronasally with parvoviruses. First, virus replication occurs in the mucous membranes, then followed by viraemia. The lymphatic system and organs become infected.
In dogs, parvovirus infection usually progresses as a cyclic systemic disease with a manifestation in the intestinal epithelium and the resulting clinical picture of anorexia, fever, vomiting and persistent bloody diarrhoea. The disease is most severe in puppies.
Different clinical forms of parvovirus infection can develop. The peracute form results in death within a few hours, usually without any serious signs. The acute form, however, is characterised by severe symptoms. High fever, severe bloody diarrhoea and vomiting occur. Due to the high affinity of the virus to tissues with high mitotic activity, severe leukopenia occurs simultaneously. If the leucocyte count falls below 2000 cells/μl, prognosis must be made carefully. Subclinically infected animals represent the pathogen reservoir as they shed the virus via the faeces.
Feline parvovirus infection – panleukopenia – is a highly contagious systemic disease of felids. The mortality rate among unvaccinated animals is over 80%.
Clinically, the disease is characterised by fever, diarrhoea, vomiting and dehydration. The blood count shows extreme leukopenia. A special case is the intrauterine infection. The mother cat is infected without showing any symptoms, but it leads to the abortion or death of the kittens. If kittens are born alive, there is often a cerebellar hypoplasia, which leads to ataxia and tremor, usually without any impairment of consciousness.
Aleutian mink disease is caused by a parvovirus. This single-stranded DNA virus is non-enveloped and therefore, like canine and feline parvoviruses, extremely resistant. Minks, but also ferrets, skunks, otters, raccoons, foxes etc. can be affected by this disease.
The virus triggers an immune complex-mediated disease which is mainly characterised by hypergammaglobulinaemia. The signs vary: Young animals tend to develop pneumonia, adult animals develop glomerulonephritis, arteritis, and/or meningoencephalitis. Bloody diarrhoea, hind leg paresis and fertility disorders have further been described. The outcome is often lethal.
As there is currently no vaccine available, many ferrets are vaccinated with dog vaccines; it is unlikely that this will provide protection against an infection with the Aleutian mink disease virus.
Transmission can be both direct and indirect.
Equine serum hepatitis, formerly referred to as Theiler’s disease, is caused by infection with equine parvovirus-hepatitis virus (EqPV-H). EqPV-H is a hepatotropic single-stranded DNA virus that can cause hepatitis in infected horses. Asymptomatic infection is common. Approximately 2% of infected horses develop clinical hepatic disease, ranging from mild disease to acute fulminant liver failure. Clinical signs may include one or more of the following: lethargy, anorexia, jaundice, neurological signs associated with hyperammonaemic encephalopathy, death usually within 72 hours.
EqPV-H should be suspected in horses with signs of illness and/or liver disease. Horses between 3 – 6 years of age have a seroprevalence of about 14%, for the age group of 11 – 15 years even a value of about 43% has been reported. EqPV-H-positive horses have often received a blood product 4 – 8 weeks before.
Porcine parvovirus (PPV) can be detected in almost all swine populations worldwide. In Germany, a prevalence of 60 – 80 % can be assumed.
In an infection with PPV, fertility disorders and embryonic infections with subsequent fetal death (SMEDI: stillbirth, mummification, embryonic death, infertility) are the main clinical symptoms. The sows usually show no clinical signs.